There are few 'second-line' drugs available for the treatment of PSA and their use is often limited by toxicity. Thirty-nine patients with active PSA recruited from two rheumatology units were randomly allocated to either enteric-coated sulphasalazine (SASP) or placebo and followed for 24 wk. Six patients in the SASP group and 11 on placebo discontinued therapy before 24 wk. Evaluation of effect of treatment revealed significant improvements in articular index in both groups at 12 wk. By 24 wk the articular index in placebo group was still showing benefit. In addition to articular index the SASP group improved significantly in terms of visual analogue scale, duration of morning stiffness and ESR. SASP is effective in PSA but the partial clinical response to placebo indicates the importance of placebo-controlled studies in this variable disease.